Tiny Microbes

The RV Investigator is currently undertaking oceanographic research along the 110°E meridian off Western Australia as part of the second International Indian Ocean Expedition. The voyage is led by Professor Lynnath Beckley of Murdoch University and the research is supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility.

Date: May 18, 2019

Time: 1200 AWST

Latitude: 38°S

Longitude: 110°E

Wind direction: N

Wind speed: 15 knots

Swell direction: SW

Depth: 4266 m

Air temperature: 13.7°C

Sea temperature: 13.8°C

Notes: Station 1 is done and dusted. It was a very busy day with lots of samples and data collected by many satisfied scientists.

Tiny Microbes, Big Impact

By Dr Martin Ostrowski

Microbes are everywhere, they’re in the soil, on our skin, in our guts and they live in the ocean in incredible numbers. In a similar role to our gut microbes, which are keeping us healthy, research has revealed that ocean microbes play important roles sustaining our planet. What are these microbes and what are they doing? Onboard RV Investigator a team of microbiologists is addressing these questions using modern molecular methods. They aim to identify which microbes are present and determine how they thrive and interact with other species. This work will help us understand how these tiny organisms support the production of food in the ocean, which feeds over 1 billion people, and ultimately plays a fundamental role keeping our planet healthy.

Most marine microbes are planktonic, but surprisingly, they fundamentally shape their surroundings by transforming over 90% of all organic matter, driving major elemental and geochemical cycles, and making and breaking chemical compounds that have a direct effect on climate. What they lack in size, they make up for in sheer numbers.

The activity of microbes impacts on all levels of the marine systems, from water chemistry and primary production, which ultimately supports all marine life, through to regulating climate and playing a role in the health of the largest mammals on the planet. Over geological time, free-living marine microbes have been the main source of power for the planet. By modern estimates, approximately half of all primary production occurs in the oceans. In very general terms, this means that marine microbes are like the lungs of the planet, but in reverse, drawing in carbon dioxide and releasing oxygen for us to breathe.

In the CTD room, several scientists retrieve water samples from the Niskin bottles for microbial analyses. In the foreground from left, Amaranta Focardi (Macquarie University) documenting the details and James O’Brien (University of Technology Sydney) and Dr Peter Thompson (CSIRO) taking water from the rosette. Photo: Micheline Jenner.

Microbes are invisible to the naked eye, especially the single-celled species, which make up the bulk of ‘biomass’ in the oceans. Much of the work done in the microbiology lab involves flow cytometry and high-throughput genome sequencing of water samples collected from different depths using the CTD rosette of Niskin bottles. We use the cytometer to count different types of bacteria, cyanobacteria, micro algae and virus particles. There are more than one million microbial cells in each millilitre of seawater, and 10 times more viruses! Sequencing of microbial marker genes provides estimates of total diversity in the Australian marine microbiome.

Pramita Ranjit (Macquarie University) filters water in one of the laboratories on the RV Investigator to determine the microbiome of the south-east Indian Ocean at the first station on the 110° East line. Photo: Micheline Jenner.